In the Tang and Song Dynasties, Xuanzhou became the national
writing-brush-producing center, whose products were called "Xuan-bi", and
"Zhuge-bi" was the best in quality in Xuanzhou. After the Yuan Dynasty the
brush-producing industry of Huzhou boomed, and "Hu-bi" replaced "Xuan-bi". The
characteristics of "Hu-bi" were sharp, neat, round and tough.